<?php
// +----------------------------------------------------------------------
// | YwxApp [ WE CAN DO IT JUST THINK ]
// +----------------------------------------------------------------------
// | Copyright (c) 2026-2036 http://ywxapp.cn All rights reserved.
// +----------------------------------------------------------------------
// | Author: ywxapp<admin@ywxapp.cn>
// +----------------------------------------------------------------------
declare (strict_types = 1);

namespace addon\docs\service;

use addon\docs\model\DocsDoc;
use addon\docs\model\DocsSearch;

/**
 * 文档搜索服务
 *
 * 索引表保存正文纯文本副本，避免每次搜索都对 longtext 富文本做 LIKE。
 *
 * @author ywxapp <admin@ywxapp.cn>
 */
class DocSearchService
{
    /**
     * 摘要截取长度
     */
    const SNIPPET_LENGTH = 120;

    /**
     * 写入 / 更新单篇文档索引
     *
     * @param DocsDoc|array $doc 文档模型或数组
     * @return void
     */
    public static function index($doc): void
    {
        $data = $doc instanceof DocsDoc ? $doc->toArray() : (array) $doc;
        $id   = (int) ($data['id'] ?? 0);
        if ($id <= 0) {
            return;
        }

        // 纯目录节点或隐藏文档不进索引
        if ((int) ($data['is_dir'] ?? 0) === 1 || (int) ($data['status'] ?? 1) !== 1) {
            self::remove($id);
            return;
        }

        $plain = self::toPlainText((string) ($data['content'] ?? ''));

        $payload = [
            'doc_id'     => $id,
            'project_id' => (int) ($data['project_id'] ?? 0),
            'version_id' => (int) ($data['version_id'] ?? 0),
            'title'      => (string) ($data['title'] ?? ''),
            'keywords'   => (string) ($data['seo_keywords'] ?? ''),
            'plain_text' => $plain,
        ];

        $exists = DocsSearch::where('doc_id', $id)->find();
        if ($exists) {
            $exists->save($payload);
        } else {
            DocsSearch::create($payload);
        }
    }

    /**
     * 删除单篇文档索引
     *
     * @param int $docId 文档ID
     * @return void
     */
    public static function remove(int $docId): void
    {
        if ($docId > 0) {
            DocsSearch::where('doc_id', $docId)->delete();
        }
    }

    /**
     * 重建全部索引
     *
     * @param int $projectId 限定项目，0 表示全部
     * @return int 已索引条数
     */
    public static function rebuild(int $projectId = 0): int
    {
        $query = DocsDoc::where('status', 1)->where('is_dir', 0);
        if ($projectId > 0) {
            $query->where('project_id', $projectId);
        }

        $count = 0;
        $query->chunk(100, function ($docs) use (&$count) {
            foreach ($docs as $doc) {
                self::index($doc);
                $count++;
            }
        });

        return $count;
    }

    /**
     * 执行搜索
     *
     * @param string $keyword   关键词
     * @param int    $projectId 限定项目，0 表示全部
     * @param int    $limit     返回条数
     * @return array
     */
    public static function search(string $keyword, int $projectId = 0, int $limit = 30): array
    {
        $keyword = trim($keyword);
        if ($keyword === '') {
            return [];
        }

        // 转义 LIKE 通配符，防止用户输入 % 造成全表扫描
        $escaped = str_replace(['\\', '%', '_'], ['\\\\', '\%', '\_'], $keyword);
        $like    = '%' . $escaped . '%';

        $query = DocsSearch::alias('s')
            ->join('docs_doc d', 'd.id = s.doc_id')
            ->join('docs_project p', 'p.id = s.project_id')
            ->join('docs_version v', 'v.id = s.version_id')
            ->field('s.doc_id,s.title,s.plain_text,d.name as doc_name,p.name as project_name,p.title as project_title,v.name as version_name')
            ->where('d.status', 1)
            ->where('p.status', 1)
            ->where(function ($q) use ($like) {
                $q->whereLike('s.title', $like)
                    ->whereOr('s.keywords', 'like', $like)
                    ->whereOr('s.plain_text', 'like', $like);
            });

        if ($projectId > 0) {
            $query->where('s.project_id', $projectId);
        }

        $rows = $query->limit($limit)->select()->toArray();

        foreach ($rows as &$row) {
            $row['snippet'] = self::snippet((string) $row['plain_text'], $keyword);
            unset($row['plain_text']);
        }
        unset($row);

        return $rows;
    }

    /**
     * HTML 转纯文本
     *
     * @param string $html 富文本
     * @return string
     */
    public static function toPlainText(string $html): string
    {
        if ($html === '') {
            return '';
        }
        // 先移除脚本与样式，避免其内容混入正文
        $html = preg_replace('#<(script|style)\b[^>]*>.*?</\1>#is', ' ', $html) ?? $html;
        // 块级标签替换为空格，防止相邻段落文字粘连
        $html = preg_replace('#<(br|/p|/div|/li|/h[1-6]|/tr)\s*/?>#i', ' ', $html) ?? $html;
        $text = strip_tags($html);
        $text = html_entity_decode($text, ENT_QUOTES | ENT_HTML5, 'UTF-8');
        $text = preg_replace('/\s+/u', ' ', $text) ?? $text;
        return trim($text);
    }

    /**
     * 生成命中摘要
     *
     * @param string $text    纯文本
     * @param string $keyword 关键词
     * @return string
     */
    protected static function snippet(string $text, string $keyword): string
    {
        if ($text === '') {
            return '';
        }

        $pos = mb_stripos($text, $keyword, 0, 'UTF-8');
        if ($pos === false) {
            return mb_substr($text, 0, self::SNIPPET_LENGTH, 'UTF-8');
        }

        $start   = max(0, $pos - 40);
        $snippet = mb_substr($text, $start, self::SNIPPET_LENGTH, 'UTF-8');

        return ($start > 0 ? '...' : '') . $snippet . '...';
    }
}